irj  18,  1918. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY     CIRCULAR  No.  169. 

L.  O.   HOWARD.  Enlomolotiirt  »nd  Chief  ol  Burcu. 


SACBROOD, 

A  DISEASE  OF  BEES, 


ny 


G.  V.  WHITE,  M.  I)..  Ph.  D., 


WMHIN^TON  :  GOVERNMENT  PRINTING  OFFICE   !  lilt 


BUREAU  OF  ENTOMOLOGY. 

L.  O.  Howabd,  Entomologist  and  Chief  of  Bureau. 

C.  L.  Maklatt,  Entomologist  and  Acting  Chief  in  Absence  of  Chief. 

R.  S.  Clifton,  Executive  Assistant. 
w.  F.  Tastet,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  truck  crop  and  -stored  product  insect  investigations. 

A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 

W.  D.  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 

F.  M.  Webster,  in'charge  of  cereal  and  forage  insect  investigations. 

A.  L.  Quaintance,  in  charge  of  deciduous  fruit  insect  investigations. 

E.  F.  Phillips,  in  charge  of  bee  culture. 

D.  M.  Rogers,  in  charge  of  preventing  spread  of  moths,  field  work. 

Roll*.  P.  Currie,  in  charge  of  editorial  work. 

Mabel  Colcord,  in  charge  of  library. 

Investigations  in  Bee  Culturj  . 

E.  F.  Phillips,  in  charge. 

G.  F.  White,  J.  A.  Nelson,  experts. 

G.  S.  Demuth,  A.  H.  McCray,  N.  E.  McIndoo,  apicultural  assistants. 

D.  B.  Casteel,  collaborator. 
Pearle  H.  Garrison,  preparator. 

ii 


Circular  No.  169.  ImatA  Jtnoarj  16,  1013. 

United  Stales  Department  of  Agriculture, 

BUREAU  OF  ENTOMOLOGY. 

L.  O.  HOWARD,  Entomologist  and  Chief  ol  Bureau. 


SACBBOOD,   A  DISEASE  OF  BEES. 

r.\  G,  I.  White,  .\i.  i  >..  rii.  n.  Expert  m  Bacteriotooy, 

l\  ll:ol>l  <    I  l(i\. 

The  purpose  of  this  preliminary  paper  i-  to  disease  briefly  a  dis- 
ease, which  has  been  recognized  by  the  bee  keeper-  for  many  years 
as  dead  brood,  that  i-  different  From  foul  brood. 

Sacbrood,  therefore,  is  no  new  disease.  Samples  of  it  have  been 
received  from  all  the  States  except  three,  together  with  samples  from 
Canada.  This  disease  really  has  had  no  name.  In  recent  years  many 
bee  keepers  have  by  mistake  spoken  od  it  a-  "  pickled  brood."     The 

pickled  brood  a-  William  R.  I  low  aid  describes  it.  however,  i-  a   \ei\ 

different  disease.  Before  considering  sacbrood  it  might  lie  well  to 
explain  briefly  what  is  meant  by  pickled  brood. 

l'l<  SUED  BBOOD. 

In  1S!)C>  William  R.  Howard,  of  Texas,  wrote  a  paper  in  which  he 
describes  a  disease  of  bees  that  he  call-  "  pickled  brood."  He  de- 
clared in  his  paper  that  the  disease  was  caused  by  a  fungus  to  winch 
he  gave  the  name  Aspergillus  pottirtf.  In  1898  he  wrote  a  9econd 
paper  in  which  he  says  that  the  fungus  may  attack  not  only  the 
larvae  and  pupa?  but  adult  bees  a-  well. 

M  i.i—  en  in  1906  mentioned  a  disease  of  bees  which  he  says  is  caused 
by  a  fungus  Btated  by  him  to  he  similar  to  Aspergillus  ftavus  ami 
easily  isolated  from  the  larva',  pupae,  and  adult  bees  affected  by  the 
disease. 

These  two  men.  then.  Howard  and   Maa—en.  have  each  written  of 

a  disease  of  bees  which  they  believe  to  he  caused  by  a  fungus.     By 

each  it  is  claimed  that  the  fungus  can  attack  adult  bees  a-  well  a-  the 
larva?  and  pupa'.  Howard  named  the  disease  which  he  mentioned 
"pickled  brood,"  and   bfaassen   referred   to  the  disease  which   at- 


1  This  .-irrui.ir  will  be  followed  by  ii  bulletin  ..f  thi<  bureau  in  which  this  d 
be  treated  more  fully. 


2  SACBROOD,   A   DISEASE   OF   BEES. 

tracted  his  attention  as  an  "  aspergillusmycosis  in  bees."  The  dis- 
eases, as  described  by  Howard  and  Maassen.  then,  would  be  called 
fungous  diseases. 

II'  there  are  any  such  fungous  diseases  of  bees  in  the  United  States 
they  have  not  yet  attracted  the  attention  of  the  bee  keepers.  I  base 
this  conclusion  upon  the  fact  that  during  my  study  of  bee  disease- 
there  has  not  yet  been  received  from  the  bee  keepers  any  sample  that 
could  be  considered  a  fungous  disease.  If  future  investigations 
demonstrate  that  there  exists  a  fungous  disease  like  the  one  Howard 
has  described,  then  the  name  "  pickled  brood  "  can  be  used  to  desig- 
nate it.  When  using  the  term  "pickled  brood"  in  the  future  the 
possible  disease,  condition  described  by  Howard  will  be  meant. 

A   DISEASE   OF   THE   BROOD   WHICH    IS    NOT   FOIL   BROOD. 

There  is  a  disease  of  the  brood  of  bees  that  has  attracted  consid- 
erable attention  among  bee  keepers  that  is  neither  American  foul 
brood,  European  foul  brood,  pickled  brood,  chilled  brood,  nor 
starved  brood.  This  disorder  of  the  brood  has  for  many  years  been 
recognized  by  bee  keepers  as  being  different  from  foul  brood.  Doo- 
little,  of  America,  in  1881  wrote  of  a  disease  which  he  says  is  similar 
to  and  called  foul  brood  but  which  is  not  foul  brood.  He  writes  that 
the  larvae  die  here  and  there  throughout  the  brood  comb  and  that 
the  disease  may  disappear  entirely  or  it  may  reappear  the  next  sea- 
son. Jones,  of  Canada,  in  1883  wrote  also  of  a  disease  which  results 
in  a  dying  of  the  brood,  with  appearances  similar  to  foul  brood;  but 
he  states  that  the  disease  is  not  foul  brood.  He  says  that  the  bees 
frequently  remove  the  dead  brood  and  that  no  further  trouble  ensues, 
Simmins,  of  England,  in  1887  wrote  of  dead  brood  which  he  says  is 
not  foul  brood,  and  describes  the  difference  in  appearance  between 
the  brood  dead  of  the  disease  and  brood  dead  of  foul  brood.  He 
states,  furthermore,  that  the  condition  is  different  from  chilled  brood 
and  that  Cheshire  did  not  find  any  microscopic  evidence  of  disease 
in  larvae  dead  of  the  disease.  An  editorial  in  one  of  the  bee.  journals 
in  1892  is  of  particular  interest  at  this  point.  The  editor  wrote  that 
he  had  recently  encountered  dead  brood  which  did  not  seem  to  be 
infectious  and  which  lacked  two  decisive  symptoms  of  the  real  foul 
brood,  viz.  the  ropiness  and  the  glue-pot  odor. 

My  own  study  of  this  dead  brood,  recognized  by  the  bee  keepers 
as  being  different  from  foul  brood,  was  begun  in  1902.  Eight  sam- 
ples labeled  "  pickled  brood  "  were  received  from  the  bee  inspectors 
of  New  York  State  during  1002  and  1003.  These  samples  were  ex- 
amined and  were  found  to  be  practically  free  from  microorganisms. 
The  results  of  these  examinations  were  published  in  January.  1004. 
Burri.  of  Switzerland,  in  1000  reported  the  results  of  the  examination 
of  25  samples  of  brood  material  thought  by  the  bee  keepers  to  be 


BROOD,    \    DISEA8E    OF    B]  I  3.  0 

diseased.  He  placed  the  results  of  his  examinations  under  the  follow- 
ing headings:  "Sour  brood,"  "stinking  foul  brood,"  "nonstinking 
foul  brood,"  and  "*  < l»-:i « 1  brood  free  from  bacteria."  Pour  <>f  ili«'  25 
sample-  examined  contained  dead  brood  free  from  bacteria  and  unac- 
companied by  other  diseases.  Kiirsteiner,  of  Switzerland,  in  L910, 
in  classifying  the  results  obtained  from  -:i 1 1 1 j »K •-  examined  by  him, 
made  the  -nine  classification  as  made  by  Burri.  During  the  past  six 
826  samples  of  this  disease  have  been  received  by  the  Bureau 
of  Entomology  and  diagnosed  in  it-  bacteriological  laboratory. 

There  is,  therefore,  n  disorder  attacking  the  brood  <>f  bees  in  which 
brood  dies,  but  in  which  there  has  n<>t  been  demonstrated  anj  micro- 
organism to  which  tlic  cause  of  the  trouble  could  be  attributed.  For 
this  disease  the  name  of  "sacbrood  "  is  here  suggested. 

rm    \  \  mi    BAI  BBOOD. 

A-  stated,  my  first  examination  of  this  dead  brood  was  made  in 
1902,  when  samples  were  received  <  1  i :•  !_rii<>-«-. I  by  bee  keepers  as 
"pickled  brood."  The  fad  was  easily  determined  at  thai  time  that 
tin-  disease  could  not  lie  considered  n  fungous  disease  and  was  there- 
fore not  pickled  brood.  In  the  past  m\  preference  has  been  to  refer 
to  this  condition  only  as  the  "  -o-called  pickled  hrood."  Since  the 
<1  i~.:i-t-  is  not  pickled  hrood.  it  will  produce  less  confusion  and  he 
more  scientific  if  the  term  "pickled  brood "  he  entirely  omitted  in 
the  mime  for  the  disease.  Many  larvae  dead  of  this  disease  can  he 
removed   from  the  cell  without   rupturing  their  body  w;ill.     When 

thus  removed  they  have  the  appearance  of  a  -mall  closed  sac.  This 
character  suggested  the  name  "sacbrood."  The  name  has  the  virtue. 
therefore,  of  being  both  appropriate  ami  brief. 

l  Hi:  -1  MPTOM8  "i    -  v  BBOOD. 

The  strength  of  a  colony  in  which  sacbrood  is  present  is  frequently 
not  noticeably  diminished.  When  the  brood  i-  badly  infected,  how- 
ever, the  colony  naturally  becomes  appreciably  weakened  thereby. 
The  hrood  die-  after  the  t  imc  of  capping.  The  dead  larva'  are  there- 
fore almost  always  found  extended  lengthwise  in  the  cell  ami  lying 
with  the  dorsal  side  against  the  lower  wall.  It  is  not  unusual  to  find 
many  larva-  dead  of  this  disease  in  uncapped  cell-.  Such  brood, 
however,  had  been  uncapped  by  the  hee-  after  it  died.      In  tin-  disease 

the  cappings  are  frequently  punctured  by  the  hee-.  Occasionally  a 
capping  has  a  hole  through  it.  indicating  that  the  capping  itself  had 
never  been  completed.  A  larva  dead  of  this  disease  loses  it-  normal 
color  and  assumes  at  first  a  slightly  yellowish  tint.  "  Brown"  i-  the 
most  characteristic  appearance  assumed  by  the  larva  during  it-  decay. 
Various  shade-  are  observed.  The  term  "gray"  might  sometimes 
appropriately  be  \i~vA  to  designate  it.     The  form  of  the  larva  <\t'.]'] 


4  SACBROOD,   A   DISEASE   OF   BEES. 

of  this  disease  changes  much  less  than  it  does  in  foul  brood.  The 
body  wall  is  not  easily  broken,  as  a  rule.  On  this  account  often  the 
entire  larva  can  be  removed  from  the  cell  intact.  The  content  of  this 
saolike  larva  is  more  or  less  watery.  The  head  end  is  usually  turned 
markedly  upward.  The  dried  larva  or  scale  is  easily  removed  from 
the  lower  side  Avail.  There  is  practically  no  odor  to  the  brood 
combs. 

THE  INFECTIOUS   NATURE  AND  CAUSE  OF  SACBROOD. 

In  the  study  of  samples  of  this  disease  received  directly  from  bee 
keepers  no  microorganisms  have  been  found,  either  culturally  or 
microscopically,  to  which  the  cause  of  the  disease  can  be  attributed. 
This  fact,  together  with  the  fact  that  the  disease  often  disappears 
without  any  great  loss  to  the  colony,  would  tend  to  indicate  that  the 
disease  is  not  infectious.  The  experimental  evidence  which  I  have 
obtained  proves,  however,  that  the  disease  is  infectious. 

EXPERIMENTAL    WORK    WITH    SACBROOD. 

Evidence  has  been  obtained  by  me  that  sacbrood  can  be  trans- 
mitted from  diseased  to  healthy  brood.  Three  healthy  colonies  were 
inoculated  each  with  diseased  material  from  a  different  locality,  and 
in  each  of  these  three  experimental  colonies  the  disease  was  pro- 
duced. These  results  indicated  at  once  that  sacbrood  is  an  infec- 
tious disease.  The  microscopical  and  cultural  study  of  the  infected 
and  dead  brood  in  these  experimental  colonies,  as  in  the  case  of  the 
diseased  brood  in  samples  direct  from  the  apiary,  failed  to  show 
any  organism  to  which  the  cause  of  the  disease  could  be  attributed. 

This  led  naturally  to  a  study  of  the  condition  to  determine  whether 
or  not  the  virus  of  the  disease  was  so  small  that  it  had  not  been  seen. 
To  obtain  evidence  on  this  point  material  containing  the  virus  was 
filtered,  using  an  earthenware  filter.  The  three  colonies  in  which 
the  disease  had  been  produced  experimentally  furnished  the  disease 
material  for  the  experiments.  Larvae,  sick  and  dead,  of  sacbrood 
were  picked  from  the  combs,  crushed,  and  diluted  with  sterile  water. 
This  suspension  was  filtered  by  the  use  of  the  Berkefeld  filter.  From 
each  of  the  three  diseased  colonies  a  separate  filtrate  was  obtained, 
which  was  fed  in  sirup  to  healthy  colonies.  Six  colonies  were  thus 
fed — two  with  each  of  the  three  separate  filtrates.  As  a  result  of 
these  inoculations  sacbrood  with  typical  symptoms  of  the  disease  was 
produced  in  all  of  the  six  colonies  thus  fed. 

One  more  experiment  will  be  mentioned  at  this  time.  In  this  the 
diseased  brood  used  was  taken  from  one  of  the  colonies  in  which 
the  disease  had  been  produced  by  feeding  filtrate.  Disease  material 
from  this  colony  was  filtered  as  before  and  fed  to  two  healthy  colonies, 


BROOD,    \    DISE  \>i     OF   BEES. 

with  the  result  thai  sacbr i  was  produced  in  each.     It  might   be 

mentioned  here  also  that  other  experiments  made  indicate  that  the 
virus  i->  killed  by  the  application  of  a  comparatively  small  amount 
of  heat  ■ 

l  ii  colonies,  therefore,  Bacbrood  has  been  produced  experiment 
ally  by  feeding  t<>  healthy  colonies  the  virus  of  this  di  <;i~c.  In  B 
of  the  11  colonies  the  disease  was  produced  by  virus  that  had  passed 
through  the  Berkefeld  filter.  The  disease,  therefore,  which  bee 
keepers  have  for  a  long  time  recognized  as  being  different  from  either 
American  or  European  foul  brood  Im^  now  been  demonstrated  to  be 
:in  infectious  disease  that  is  caused  by  a  filterable  \ini-. 

The  conclusion  to  lxv  drawn  from  thi>  work,  therefore,  is  that 
Bacbrood  is  an  infectious  disease  of  the  brood  <>f  bees  caused  bj  an 
infecting  agent  thnt  is  so  small,  or  of  such  m  nature,  ihnt  it  will 
l>;i-^  through  the  pores  of  a  Berkefeld  filter. 

The  three  principal  brood  diseases,  thru,  are  now  :ill  known  to 
be  infectious.  These  diseases  are:  American  foul  brood,  caused  by 
Hit,  illns  larvce;  European  foul  .brood,  caused  by  BaciUtu  pluton; 
niitl  sacbrood,  caused  by  a  filterable  virus. 

Approved : 

James  Wn  a  »n, 

S    n  inn/  of  ■  Igrit  ultun  . 

Washington,  I).  ('..  December  /"  1912. 


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